A standard type of housing or carrier for an integrated circuit chip comprises a rectangular body of insulating material having outwardly facing chip carrier side surfaces on which there are provided contact pads or leads which extend from conductors that in turn extend to the integrated circuit chip contained in the chip carrier. When the chip carrier is tested prior to its being placed in service, it is placed in a chip carrier socket temporarily while "burn-in" and tests are carried out. Chip carrier sockets of this type are commonly referred to as "burn-in" sockets and they are used repeatedly for the reason that chip carriers having integrated circuits therein are usually tested at elevated temperatures before being placed in service. After the chip carrier has been tested, it is placed permanently in a chip carrier socket on a circuit board or the like which may be part of electronic equipment.
A known type of chip carrier socket comprises a socket body of insulating material having a recess therein which receives the leadless chip carrier and having contact terminals therein which engage or contact the contact pads on the chip carrier when the chip carrier is placed in the recess. The contact force or contact pressure with which each of the contact terminals engages the contact pads on the chip carrier is an important consideration. This contact force can be relatively low if the contact surfaces are all plated with gold, however, it must be relatively higher if the surfaces are tin plated. In either event, it is important that this contact force be closely controlled in the equipment in which the chip carrier is used. Chip carrier sockets are therefore designed in some instances to have a relatively high contact force and for this reason it is usually difficult to insert the chip carrier into the chip carrier socket; in other words the chip carrier can be placed in the socket only with a relatively high insertion force. The chip carrier socket can be designed such that only a low insertion force is required and insertion is therefore easily carried out if the contact surfaces are gold plated. In either event, the contact force must be controlled carefully when the chip carrier is designed and manufactured.
It would be desirable to have a chip carrier socket having zero insertion force (ZIF) characteristics or low insertion force (LIF) characteristics and in addition having a means closely to control the contact force exerted by the contact terminals in the chip carrier against the contact pad surfaces on the chip carrier. A chip carrier socket having zero or low insertion force characteristics would simplify the operation of placing the chip carrier in the socket recess. At the same time, it would be then possible to achieve a predetermined contact force after the chip carrier was placed in the socket. A chip carrier socket of this type would be particularly desirable in "burn-in" type socket applications because of the fact that the socket is used repeatedly in burn-in and in testing newly manufactured chip carriers. It would also be desirable in those chip carriers used in electronic equipment for the reason that it would facilitate assembly of the chip carrier in the chip carrier socket and permit the operation to be carried out with robotic devices.
It would also be desirable to have a chip carrier socket having an ejection feature for removing the chip carrier from the socket after "burn-in" or at other times should the need arise. The provision of a chip carrier ejector on the socket would be particularly desirable for "burn-in" sockets again because of the fact that a burn-in socket is used repeatedly.
The present invention is directed to the achievement of an improved chip carrier socket having LIF characteristics or ZIF characteristics coupled with a means of controlling the contact force which is exerted on the contact pads of the chip carrier by the terminals in the chip carrier socket. The invention is further directed to the achievement of a chip carrier socket having an ejector means which facilitates removal of the chip carrier from the recess in the chip carrier socket.